GPU really broken? Video system failure (SPECIFIC en DETAILED)

Hi

How it was: For some time my Acer has been doing the "one long, two short beeps", on startup, refusing to boot. After unplugging-replugging the video cable or waiting some hours it would work again. It has also been crashing (BSOD, but no monitor signal to actually see it) after some minutes of gaming (heavy graphics games). at that time everything worked fine (while not playing heavy games)

I discovered that the video card was overheating, getting at 100c. I also knew in AMI Bios language "one long two short" means video system failure ("An error was encountered in the video BIOS ROM, or a horizontal retrace failure has been encountered").

What I did: opened the case to increase airflow. this allowed me to keep gaming (occasionally) reaching critical temperatures but not extreme as before. No crashes, no BSOD. after few days however I decided to do something about the temperature. I bought gold thermal paste and replaced with the (old) thermal paste on both CPU and GPU, hoping this would make the difference, alongside an extra fan.

How it is now: when the monitor is connected to the graphics card, and I start the computer, the monitor receives no signal, and the bios does the "one long two short beeping". The computer does not start. When I connect the monitor to the VGA onboard graphics card, same thing. When I REMOVE the graphics card, and connect the monitor to the "standard VGA graphics adapter" on the motherboard. Everything works fine. Windows starts, and although graphics and resolution are crappy, I can use the PC.

Is my graphics card really broken?
Could it be it is an GPU video BIOS issue and not hardware?



I already tried:

Reseating RAM (just one stick)
Doing extensive Memtest. no memory issues.
Reseating Graphics Nvidia Graphics card
Dusting, unplugging-replugging of cables


My PC:

Acer Aspire X5900 (desktop)
CPU: Intel core i5 CPU 650 @ 3,2 GHz
RAM: 4,00 GB Dual-Channel DDR3 @ 664MHz (9-9-9-24) (1 stick)
Bios: AMI BIOS P01-A3 12/16/2009
Motherboard: Acer FIH57 (CPU 1)
OS: Microsoft Windows 7 Home Premium 64-bit SP1
Graphics Card: Nvidia Geforce GT 320 1GB
Onboard GC: Standard VGA Graphics Adapter